Multifunctional monomers, m-xylylenedimaleimide, p-phenylenedimaleimide, m-phenylenedimaleimide, and p-phenylenedinadimide, all of which have maleimide groups, were synthesized to increase thermal and radiation stabilities. The synthesized multifunctional monomers showed good compatibility with low-density polyethylene (LDPE). Mixtures of LDPE and these multifunctional monomers were irradiated with gamma-rays from a Co-60 source at room temperature in a nitrogen atmosphere. The absorbed dose ranged from 0 to 160 KGy. Among these multifunctional monomers, m-xylylenedimaleimide was the best in gel fraction enhancement. Crosslinked LDPE with m-xylylenedimaleimide displayed a higher modulus than that of crosslinked LDPE with triallyl cyanurate. For the elongation property, LDPE with m-xylylenedimaleimide as a multifunctional monomer showed better results than that with commercial multifunctional monomers such as triallyl cyanurate (TAC), and trimethylol propane triacrylate (TMPTA). (C) 2003 Wiley Periodicals, Inc.